Circuit breaker



June 21, 1949' H. G. BAXTER 2,473,848

CIRCUIT BREAKER 4Filed Aug. 21, 1947 #2f NJ) il ATTORNEY Patented June 21, 1949 CIRCUIT BREAKER Harold Baxter, Baldwin, N. Y., assignor to lWestinghouse Electric Corporation, East Pittsbui-gh, Pa., a corporation of Pennsylvania Application August 21, 1947, Serial No. '169,915

This invention relates to circuit breakers and more particularly, to circuit breakers that are tripped open automatically in response to overload currents.

One object of the invention is to provide a circuit breaker embodying improved means for causing quick opening and closing of the breaker contacts.

Another object of the invention is to provide a circuit breaker embodying an improved operating mechanism including an operating handle extendingthrough an opening in the breaker housing and an overcenter spring operable by the handle to open and close the breaker, which overcenter spring also provides pressure to seal the handle opening in the housing.

Another object of the invention is to provide a circuit breaker wherein an overcenter operating spring provides pressure to seal the handle opening in all positions of the handle.

Another object of the invention is to provide an improved circuit breaker construction that is simple, reliable in operation and relatively inexpensive to manufacture.

The novel features that are considered characteristic of the invention are set ijorth in partieular in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof, will best be understood from the following description thereof when read in conjunction with the accompanying drawing.

In said drawing:

Figure 1 is an elevational sectional view taken on line I--I of Fig. 2 through a circuit breaker embodying the principles of the invention;

Fig. 2 is a sectional view taken on line II-II of Fig. 1 and looking in the direction of the arrows.

Referring to the drawing, the circuit breaker is encased in a housing comprising a base portion II of molded insulating material and a cover plate I3 also of insulating material. A stationary contact l5 is rigidly mounted on an upturned portion of a conductor I1 vsecured by means of a screw I9 to the base II. The conductor extends through the end wall of the housing Where it is provided with a terminal screw 2l for connecting the breaker in an electrical circuit.

A movable contact 23, which cooperates with the stationary contact l5 to open and close the circuit, is rigidly mounted on an ear formed over at right angles from a switch arm 21. The switch arm 21 is pivotally mounted on a pivot 11 Clainis. (Cl. Z110-116) pin 29, the ends of which are supported respectively in an opening in a boss 9| (Fig. 2) formed integral with the base Il and a corresponding opening in a boss 33 formed integral with the cover plate I3. Pivotally mounted on a pivot pin 35 on the switch arm 21 is a latch 31 which is biased by means of a spring 39 into engagement with a pin 4l projecting from an operator 43. The operator 43 is biased by means of an overeenter operating compression spring 45 to a closed position (Fig. 1) in which, by means of the'pin 4I and latch 31, it holds the switch arm 21 in closed contact position and supplies the contact pressure between the contacts l5 and 23.

The overcenter spring 45 is coiled about a spring guide 41 having one end bifurcated as at 49 to slide over a headed pin 5l projecting laterally from the upper end of the operator 43. The other end of the spring guide 41 is pivotally mounted on a pivot pin 53 supported between a pair of spaced projections 55 molded integral with a sliding plate 51 of molded insulating m'aterial. The plate 51 is mounted for longitudinal sliding movement in a pair oi opposing channels 59 formed by projections 6| one of which is molded integral `with the base Il and the other ,of which is molded integral with the cover plate I3. The slide 51 is provided with a handle 63 projecting outwardly through a slot G5 in the housing whereby the slide may be manually moved to an 01T position and to an on position to manually open and close the breaker.

The overcenter spring 45 is compressed with an initial compression between a shoulder 61 on the spring guide 41 and a washer 69 encircling the spring guide and bearing against the upper rounded end of the operator 43 and the head of the pin 5l (see Fig. 2).

In order to operate the circuit breaker to manually open the contacts, the `slide'51 is moved, by means of the handle 63, from the on position, in which it appears in Fig. 1, to the right as far as it will go. During this movement the line of action of the compression spring 45 moves overcenter past the pivot pin 29. As soon as this occurs, the spring 45 biases and quickly moves the operator 43 in a counterclockwise direction until it is arrested by striking a shoulder 1I on a stop 13 molded integral with the side wall of the base portion of the housing. Due to the latch 31 which normally latches the switch arm 21 to the operator 43, the switch member will be moved with the operator to separate the contacts.

The circuit breaker may be manually closed 3 by moving the slide 51 in the reverse direction, that is. from the oir to the "on position during which movement the line of action of the overeenter spring 45 passes over to the left of the pin 29, whereupon the spring 49 acts to quickly move the operator 43, and through the latch 91, the switch arm 21 in a clockwise direction to close the contacts.

The circuit breaker is also arranged to be tripped open automatically in response to overload currents occurring in the circuit controlled by the breaker. To this end a bimetal trip element is provided to operate the latch 91 and release the switch arm 21 from the operator 43. The bimetal element 15 is secured by means of a mounting foot 11 to a conductor 19 which is secured to the base of the housing by means of screws 9|. The conductor 19 extends to the lett (Fig. l) through an opening in the end wall of the housing where it is provided with a terminal screw 93 for the purpose of connecting the breaker in an electrical circuit. The bimetal element 15 extends perpendicularly away from the base and is then bent at a right angle and its free end extends to the left beneath a tail 16 of the latch 31. The free end of the bimetal is electrically connected by means of a ilexible conductor 95 to a projection 91 of the switch arm 21. The high expansion side of the bimetal element is on the left and lower side so that, when heated a predetermined amount in response to overload currents, it will deflect in a direction away from the base and engage and operate the latch 31 to release the switch arm 21. When this occurs, the switch arm 21 is immediately moved to the open position by means vof a spring 99 which is coiled about the pivot pin 29 and has one end hooked over the edge of the operator 43 and the other end hooked over the edge of the switch arm, the spring 99 being tensioned in a direction to bias the switch arm 21 toward the open position. The opening movement of the switch arm 21 is limited by striking a shoulder 9| on the previously described stop 13. The tail 16 of the latch 31 is of suilicient length that it remains in contact with the pin 4| when the switch arm is in the open position. A stop 93 moulded integral with the side wall of the housing is provided to prevent more than a slight amount of clockwise movement of the operator 43 when the switch arm 21 is unlatched therefrom. The operator 43 is normally restrained in the position shown in Fig. l by the engagement of the contacts, acting through the switch arm 21, the pin 4| and latch-31. I

Before the contacts can be closed after the breaker has lbeen automatically tripped open, it is necessary to move the operator to the open position to reconnect the switch arm thereto. This is accomplished by moving the slide 51 to the o position which effects movement of the operator 43 to the off" position in the manner described in connection with the manual opening of the breaker. When the operator 43 is moved to the olf position, the spring 39 reengages the latch 31 with the pin 4| and thereafter the switch arm may be moved to the closed position in the previously described manner.

Since the handle 63 and the slide 51 are not 'displaced from the on position during an automatic opening operation, means is provided to visually indicate that the circuit breaker has been automatically tripped open. An indicator comprising a rod 95 slidably mounted in an opening -ina boss 91 molded integral with the cover plate i3 and an opening in a rib 99 also molded integral with the cover plate is normally restrained against outward movement by the engagement of a projection lili of the switch member 21 with a head |99 on the inner end of the rod 95 when the switch member 21 is in the closed position. The indicator is biased outwardly by means of a spring |99. 'I'he spring Ill is coiled about the rod 95 and is compressed between the rib 99 and a washer |95 bearing against a pin |01 extending through an opening in the rod.

Upon movement ot the switch arm 21 to the open position the projection |9| releases the rod Il permitting the spring |99 to move the indicator outwardly when the outer end thereof projects outwardly beyond the housing to indicate that the contacts of the breaker are in the open position. When the switch arm is moved to the closed position, the projection |`9| engages the head |03 and moves the rod 95 inwardly so that the outer end thereof lies approximately flush with the housing.

The operating spring 45, in addition to operating the breaker mechanism to open and close the contacts with a snap action and applying contact pressure in the closed position, also at all times presses .the slide 51 upwardly and tightly against the housing to effectively seal the handle opening 95 in the housing. This seal prevents hot ionized gases or name generated by the interruption of heavy short circuits from escaping around the handle. This protects the hand of the operator from being burned and insures that any inflammable material nearby will not be set on nre.

The breaker is trip-free of the operator in all positions of the handle, that is, the switch arm 21 may be automatically released from the operator and moved to the open position even though the handle is held in the closed position during the occurrence of an overload current.

Having described the invention in accordance with the patent statutes, it is to be understood that various changes and modifications may be made in the structural details thereof without departing from some of the essential features of the invention.

I claim as my invention:

1. A circuit breakercomprising a housing having an opening therein for receiving a handle, an operating handle disposed in said opening, a switch member movable to open and close said circuit, an operating lever for moving said switch member, a slidable member movable by said handle and closing said opening, and an overcenter compression spring operable upon movement of the handle to actuate said operating lever, said overeenter compression spring applying pressure to said slide to seal said handle opening.

2. A circuit breaker comprising a housing having an opening therein for receiving a handle, an operating handle disposed in said opening, a switch member movable to open and close said circuit, an operating lever for moving said switch member, a slidable member movable by said handle, and an overeenter spring operable upon movement of the handle to actuate said operating lever to open and closed position with a snap action, said overeenter spring at all times applying pressure to said slide to hold it in engagement with the housing and seal said handle 'opening.

3. A circuit breaker comprising a housing having an opening therein for receiving .a handle, an

operating handle disposed in said opening, a switch member carrying a contact movable to make and bleak engagement with another contact, an operating lever for moving said switch member, a slidable member movable by said handle and closing said opening, and an' overcenter spring operable upon movementl of the handle to actuate said operating lever, said overcenter spring applying force to said operating member in one direction and biasing said contacts together when in closed position and also applying a force to said slide in the opposite direction to seal the slide against said handle opening in all positions of said handle.

4. In a circuit breaker, comprising a housing, the combination of a switch member movable to open and closed positions, operating mechanism for said switch member comprising an operating lever, a manually operable slide inside the housing having a handle extending through an opening in said housing, a spring operatively relating said operating lever and said slide, said spring being operable to move said operating lever to open and closed positions to operate said switch member to open and closed position, and said spring also applying pressure to said slide and holdingv it tightly against the inside of the housing and thereby closing the opening in said housing.

5. A circuit breaker comprising a'housing having an opening therein for receiving an operating handle, an operating handle disposed for movement in said opening, a pivoted switch member movable to an open and-to a closed position, an operating lever pivoted coaxially with said switch member and operable to move said switch member, latch means releasably coupling said switch member to said operating lever, a slide mounted for reciprocable movement by said handle and closing said opening, a compression spring operable by said slide tol actuate said operating lever, said spring being disposed at all times to apply pressure between said slide and said housing to seal said opening, and a trip device operable in response to overload currents to operate said latch to permit movement of said switch member to open position even though said slide is held in closed position during the occurrence of an overload current.

6. A circuit breaker comprising a housing provided with an opening to receive an operating handle, an operating handle extending through said opening, a switch member movable to Open and closed position, an operating lever for moving said switch member, a slidable member movable by said handle between an open and a closed position, means on said housing defining opposed channels in which said slide is movable to said open and closed positions, a compression spring operable by said slide for actuating saidoperating lever and for at all times providing pressure between said slide and said housing to seal Said handle opening.

'7. A circuit breaker comprising a housing having an opening therein, a switch member movable to an open position and to a closed position, an operating lever for' moving said switch member, a slide disposed adjacent. said housing and movable to an open position and to a closed position, a handle extending through said opening for operating said slide, and spring means operativelyrelating said operating lever and said slide and operable by said slide to actuate said operating lever, said spring at all times applying a pressure between said slide and said housing to seal said opening.

8. A circuit breaker comprising a housing having an opening therein, a switch member movable to open and closed positions to open and close said circuit, an operating lever for moving said switch member, a slide disposed adjacent saidxhousing for at all times closing said opening, an operating handle secured to said slide and extending through said opening `for operating said slide, and springumeans operable by said slide to actuate said operating lever to manually open and close said circuit, said spring at all times applying a pressure to said slide to seal said opening.

9. A circuit breaker comprising a housing having an' opening therein for receiving a handle, a switch member movable to open and close said circuit, a slidable member having a handle portion extending through said opening and a closing portion for closing said opening, an overcenter compression spring operable upon movement of said handle portion to actuate said switch member, and said overcenter compression spring applying pressure to said slidable member to cause said closing portion to seal said handle opening.

10. A circuit breaker comprising a housing having an opening therein for receiving a handle, switch means movable to open and close said circuit, a slidable member having a handle portion extending through said opening and a closing portion for closing said opening, an overcenter compression spring operable upon movement of said slidable member to actuate said switch means, said overcenter compression spring applying pressure to said slidable member to cause said closing portion to seal said handle opening, and trip means for effecting automatic opening movement of said switch means in response to overload currents.

l1. A circuit breaker comprising a housing having an opening therein for receiving a handle, switch meansvmovable to vopen and close said circuit, a slidable member having a handle portion disposed in said opening and a closing portion for closing said opening, an overcenter compression spring operable upon movement of said slidable member to actuate said switch means, said overcenter compression spring applying pressure to said slidable member to cause said closing portion to seal said handle opening, and trip means operable in response to overload currents to eiiect automatic opening movement of said switch means irrespective of the closed position of said slidable member.

HAROLD G. BAXTER.

REFERENCES CITED The following references are 'of record in the iile of this patent:v 

